Georg wegner



. NITED STATES PATENT OFFICE.

GEORG WEGNER, OF BERLIN, GERMANY.

PROCESS OF ELECTROPLATING ALUMINUM.

SPECIFICATION forming part of Letters Patent No. 490,841, dated'January31, 1893. Application filed May 5, 1892. Serial No. 431,886. (Nospecimens.)

To all whom it may concern:

Be it known that I, GEORG WEGNER, a subject of the Emperor of Germany,residing at Berlin, Germany, have invented certain new andusefullmprovements in Processes of Electroplating Aluminum; and I dohereby declare the following to be a full, clear, and exactspecification.

Objects made of aluminum, that are to be galvanized, are first freed bysuch known means as potassium hydrate, &c. from all particles of grease,and after washing in clear water, and then dipped in a bath at boilingheat, containing cyanides of silver and mercury, for one to two minutes.In this process there forms a deposit of silver amalgam, on thealuminum, forming a thin fast adhering coat. The before describedprocessis necessary in order to make the aluminum, which is known to bea bad conductor, more conducting for the later galvanizing, and moreadvantageous in its operation as a cathode. Hereupon the amalgamatedaluminum is laid in a second bath in which chloride of zinc and sulphateof soda are dissolved; the anode and cathode formed by the amalgamatedaluminum are connected in the usual way with a galvanic battery of lowtension, and the latter left closed until a coating of zinc of desiredthickness is formed on the aluminum, that is, on the amalgam. After thissecond treatment the aluminum is sufficiently prepared to be coated withcopper, silver or gold, &c., in the manner usual with other metals, inwhich case. by using alloys, it is possible to give the aluminum anydesired coloring.

All attempts hitherto made to electroplate aluminum directly, have givennegative results,l oecause the silver or cyanidebaths used, which areemployed for galvanizing other metals, affected the aluminum; thealuminum is protected from the destroying action of the acids by thecoating of zinc, and can be subjected to the galvanizing process likeany other metal.

I claim:

The hereinbefore described process of galvanizing aluminum, consistingin first dipping into a bath at boiling temperature, con tainingcyanides of silver and mercury, to heighten its conductivity; thenelectrically coating with zinc, in a bath containing chloride of zincand sulphate of soda, to protect the aluminum against the acid bath incoppering, silvering, gilding, &c.

In witness whereof I have hereunto set my hand in presence of twowitnesses.

GEORG WEGNER.

Wit n esses:

R. BAYER, W. HAUPT.

